An Orbital ATK Antares rocket will lift the ninth operational Cygnus cargo resupply spacecraft into orbit for a mission to the International Space Station. The OA-9 mission will carry over three metric tons of cargo to the International Space Station as the first of two planned Orbital-ATK resupply missions in 2018 under an extension to the original Commercial Resupply Services contract to bridge a gap until CRS-2 enters operations. The Antares rocket will be flying in its upgraded 230 configuration with a pair of RD-181 engines powering its first stage and a Castor 30XL acting as second stage to lift the 6,200-Kilogram spacecraft into orbit.